Method for the chisel-less formation of boreholes for deep bores and chisel-less drilling system for carrying out said method

ABSTRACT

The invention relates to a method for the chisel-less formation of boreholes for deep bores by means of high-pressure water jet cutting. A chisel-free drilling method that makes substantially continuous drilling operation possible is characterized, according to the invention, by a combination of the processes of high-pressure water jet cutting and high-frequency rock fragmentation. The invention also relates to a chisel-free drilling system for carrying out the method.

The invention relates to a method for the chisel-less formation ofboreholes for deep bores by means of high pressure water jet cutting.Furthermore, the invention relates to a chisel-less drilling system forcarrying out said method.

Boreholes for vertical deep bores, that is to say bores which are driveninto the ground to a depth of more than 500 m, are formed in practice bythe “rotary method”, in which the rock to be penetrated is comminutedwith a scraping action by means of a rotating chisel and is continuouslyremoved by a flushing fluid which is pumped downward through the drillrod.

In the case of very deep bores, use is generally made of a drillingturbine which is arranged directly above the drill bit. In this method,the drill rod adjoining the drill bit counter to the drilling directiondoes not rotate with the drill bit but rather serves only for advancingthe bit and for supplying the flushing fluid.

Drill bits with diamond or sintered carbide edging have a durability of70 to 100 hours in customary ground conditions. In order to exchange andrefurbish the drill bit, the entire drill string then has to be pulledout of the borehole and dismantled in order subsequently to be loweredagain into the borehole with the new drill bit. In the conventional deepdrilling method, the drilling operation therefore proceedsdiscontinuously.

In order to prevent the borehole from caving in, the borehole has to besupported, which is carried out in the case of the conventional deepbores by casing. This is carried out in stages with a decreasing pipediameter in such a manner that, for example, in the case of an oil wellat a depth of 3000 m, first of all a pipe reaching to a depth of 5 m andhaving an outside diameter of 473 mm is introduced. After a drillingdepth of 150 m, a pipe known as a casing with an outside diameter of 340mm is pushed as far as the bottom of the bore and the intermediate spacebetween borehole wall and casing is filled with a cement slurry. At adrilling depth of 1500 m and at the final depth of 3000 m, furthercasing is carried out with casings which each have a smaller outsidediameter than the previous casing, and therefore the outside diameter ofthe final casing after the end depth is reached is only 140 mm.

Although this known deep drilling method has proven successful inpractice, the costs for deep bores of this type are extremely highbecause of the discontinuous drilling and the constant refurbishing orreprovisioning of the drill bits and of the drill rod.

An alternative deep drilling method of the type in question is known,for example, from DE 10 2010 005 264 A1, in which the borehole is formedin a chisel-less manner by means of water jet cutting. The drill headfor carrying out said known method is of annular design and has amultiplicity of water outlet nozzles arranged next to one another. Withthis said annular drill head, rather than comminuting the entireborehole diameter, only a rock ring is comminuted, in the manner of acore drilling machine. After a predeterminable depth of 5 m or 10 m isreached, radially inwardly facing water outlet nozzles on the drill headare activated in order radially to cut free the drill core which isexposed along the lateral area thereof. The cut-free drill core issubsequently pulled upward out of the borehole. In this known method,the borehole is lined via partial segments each spanning an arc of 120°.

Even said chisel-less drilling method operates discontinuously since thecut-free drill cores each have to be removed from the borehole.Furthermore, the borehole has to have a very large minimum diameter inorder to have the appropriate handling clearances for transporting thedrill cores.

Taking this as the starting point, the invention is based on the objectof providing a method for the chisel-less formation of boreholes, whichmakes substantially continuous drilling operation possible.

According to the invention, the achievement of this objective ischaracterized by a combination of the high pressure water jet cuttingprocess with high frequency rock fragmentation.

High pressure water jet cutting is understood as meaning the cutting upor severing of the rock with one water jet or with a plurality of waterjets under high pressure. Water jets of this type can have a pressurefrom 1000 bar. Pressures from 4000 to 6000 bar are preferably used. Anabrasive agent can be added to the water in order to increase thecutting power, this preferably being carried out only at pressures from3000 bar. Said water jets reach outlet speeds of up to 1000 m/s.

By means of the combination according to the invention of the highpressure water jet cutting with the high frequency rock fragmentation,it is possible to provide a drilling method which operates efficientlyand continuously, wherein the high frequency rock fragmentation can beoperated alternating with the high pressure water jet cutting or inparallel thereto in order to use the most effective possibility in eachcase of breaking open the rock layer to be penetrated.

In order to be able to adapt the high pressure water jet cutting processand the high frequency rock fragmentation process to each other in thebest possible manner and to the conditions required in situ in theborehole, it is proposed by the invention that the pressures of the highpressure water jet cutting process and the frequencies of the highfrequency rock fragmentation are variably adjustable.

According to an advantageous embodiment of the method according to theinvention, the inner wall of the borehole is continuously lined with areinforcement, for example a fiber-reinforced shotcrete. By means ofthis continuous lining of the borehole directly after drilling, theentire drilling operation becomes more efficient since interruptions asare required, for example, during the borehole casing known in practicecan also be omitted here.

A drilling system according to the invention for carrying out thechisel-less drilling method according to the invention is characterizedin that sonotrodes for transmitting high frequency vibrations arearranged in addition to the water outlet nozzles for the high pressurewater jet cutting on the front end side of the drill head.

According to a preferred embodiment of the invention, it is proposedthat the drill head, but at least an end plate of the drill head, whichend plate is provided with the water outlet nozzles and the sonotrodes,is designed to be rotatable about the center axis, in order to ensure auniform and substantially extensive processing over the entire boreholediameter of the rock to be penetrated.

With a practical embodiment for configuring the drilling systemaccording to the invention, it is proposed that at least one safetymodule and at least one borehole lining module are arranged behind thedrill head in the drilling direction. Depending on the application, theindividual assemblies can be arranged one behind another rigidly or soas to be movable relative to one another.

In order, in the event of a sudden rise in pressure in the borehole, forexample by drilling into a gas bubble, firstly to prevent uncontrolledescape of the gas from the borehole and secondly to prevent the entiredrilling system from being able to be pushed upward out of the boreholeby means of the rise in pressure, the safety module has at least onelocking element for the form-fitting closing of the inside diameter ofthe borehole, and clamping elements for the force-fitting securing ofthe drilling system in the borehole.

The borehole diameter can be closed in a form-fitting manner, forexample, with an expander ring which closes the borehole in order thento be able to dissipate the positive pressure in a controlled manner viasuitable pressure control valves. The clamping elements with which theentire drilling system can be interlocked in a force-fitting manner inthe borehole are designed, according to the invention, for example asbarbs which face radially upward and outward and fix the drilling systemin the respective position in the borehole.

In order to secure the borehole and also in order to shield the boreholefrom groundwater-conducting layers, the borehole is continuously lineddirectly after the drilling. For this purpose, the borehole liningmodule according to the invention has spray nozzles for applying acuring medium, such as, for example, concrete, and a reinforcing fabriclaying apparatus. In order to form said hybrid material serving forlining the borehole wall and consisting of a reinforcing fiber and acuring medium, use is preferably made of carbon fibers and concrete.According to the invention, the fiber structure can be discharged via acone, via which the reinforcing fibers can be applied directly onto theborehole wall in order subsequently to be able to be wetted with thecuring medium. Depending on requirements, the borehole can be lined witha single layer or with multiple layers.

Of course, as an alternative to the carbon fibers mentioned and theconcrete as curing medium, use may also be made of other fiber materialsand other curing media for lining the borehole.

The drilling system according to the invention, consisting of the drillhead, the safety module and the borehole lining module, isadvantageously supplied via flexible pipe and/or hose lines, via whichthe drilling system is connected to supply devices outside the borehole,wherein the pipe and/or hose lines serve for the supply and removal ofthe materials relevant to the drilling system and for the feeding in ofthe electric supply lines. Each individual line of said flexible pipeand/or hose lines is preferably designed here as an endless line whichcan be kept ready on drums.

Furthermore, it is proposed by the invention that the drive and thesteering and control apparatus for the drill head are arranged directlyon the drill head.

In order to make the drilling system according to the invention asindependent as possible from supply stations arranged outside theborehole, according to a practical embodiment of the invention the pumpsfor the high pressure water jet cutting and for sucking off the flushingmedium are arranged on the drill head and/or on the safety module.

In addition to the electric supply lines, the flexible pipe and/or hoselines, via which the drilling system is connected to supply devicesoutside the borehole, also contain data lines, for example a bus system,via which the drill head and/or the safety module and/or the boreholelining module are connected to a workplace outside the borehole.

According to the invention, via the data lines, in addition to thesystem parameters, such as, for example, feed speed and pumpingpressure, all of the ambient parameters in the borehole, such as, forexample, temperature, pressure, rock density and the like, can bedetermined via sensors coupled to the data lines and can be transmittedto the workplace in order to control the drilling system.

Finally, it is proposed by the invention that, in order to generate thehigh frequency pulses for the high frequency rock fragmentation, piezoelements which are each coupled to an amplifying unit consisting of asonotrode and an amplitude transformer are arranged in the drill head.

Owing to the equipping of the drilling system with the piezo elementsand sonotrodes in order to generate the high frequency pulses, it ispossible, after the target drilling depth is reached, to break up therock with the aid of high frequency rock fragmentation in the manner offracking, but without using chemicals.

Further features and advantages of the invention emerge with referenceto the associated drawings in which an exemplary embodiment of achisel-less drilling system according to the invention is illustratedmerely by way of example without restricting the invention to saidexemplary embodiment. In the drawings:

FIG. 1 shows a schematic side view of a chisel-less drilling systemaccording to the invention;

FIG. 2 shows a front view of the drill head according to FIG. 1, and

FIG. 3 shows a view according to FIG. 1, but showing the drilling systemin a borehole.

FIG. 1 shows a drilling system 1 for vertical deep bores, which drillingsystem essentially consists of a drill head 2, a safety module 3 and aborehole lining module 4, wherein the individual assemblies 2, 3 and 4are arranged one behind another rigidly or so as to be movable relativeto one another, depending on the application.

Although vertical deep bores are mentioned, it is possible, with themethod described below and the drilling system 1, also to direct thedrilling course from the vertical into a horizontal course if this isrequired. However, the main drilling direction is the deep verticalbore.

As is apparent from the arrangement, illustrated in FIG. 3, of thedrilling system 1 arranged in a borehole 5, the drilling system 1consisting of the drill head 2, the safety module 3 and the boreholelining module 4 is supplied via flexible pipe and/or hose lines 6, viawhich the drilling system 1 is connected to supply devices 7 outside theborehole 5. The pipe and/or hose lines 6 which serve for the supply andremoval of the materials relevant to the drilling system 1 and for thefeeding in of the electric supply lines, the individual pipe and/or hoselines 6 are designed as an endless line which can be kept ready ondrums.

The individual pipe and/or hose lines 6 are connected at certaindistances to spacers and thus form a feed-in package which is guidedinto the borehole 5. In order to be able to absorb the tensile forceswhich occur because of the dead weight of the pipe and/or hose lines 6and the weight of the drilling system 1, steel cables which areappropriately mounted outside the borehole 5 are preferably entrained.Furthermore, there is the possibility of securing floats to the pipeand/or hose lines 6, said floats absorbing the tensile loading since theborehole 5 is underwater during the drilling operation.

As is apparent from FIG. 2, water outlet nozzles 8 for the high pressurewater jet cutting and sonotrodes 9 for transmitting high frequencyvibrations for the high frequency rock fragmentation are arranged on thefront end side of the drill head 2.

In order to ensure uniform and substantially extensive processing overthe entire borehole diameter of the rock to be penetrated, the entiredrill head 2, but at least an end plate 10 of the drill head 2, whichend plate is provided with the water outlet nozzles 8 and the sonotrodes9, is designed so as to be rotatable about the center axis.

For the sucking up of the drilling mud arising during the drillingoperation, the end plate 10 is provided with suction openings 17, viawhich the drilling mud can be sucked off and pumped out of the borehole5 by the pipe and/or hose lines 6.

In order to generate the high frequency pulses for the high frequencyrock fragmentation, piezo elements which are each coupled to anamplifying unit consisting of a sonotrode 9 and an amplitude transformerare arranged in the drill head 2. In order to protect the sonotrode 9from wear, said sonotrodes are advantageously coated, for example withpolycrystalline diamond.

The pumps for the high pressure water jet cutting and for sucking offthe flushing medium are arranged on the drill head 2 and/or on thesafety module 3. In order to increase the cutting action of the highpressure water jet, an abrasive agent, such as, for example, quartzsand, can be added to the water jet, the abrasive agent being suppliedto the drill head 2 via the flexible pipe and/or hose lines 6 and beingmixed with the water jet only in the water outlet nozzle 8 in order tokeep the wear on the lines as low as possible. The abrasive agent can beadded here continuously or else only from time to time.

By means of the combination of the high pressure water jet cutting withthe high frequency rock fragmentation, and by means of the sheet-likedesign of the drill head 2 and the corresponding positioning of thewater outlet nozzles 8 and sonotrodes 9, it is possible to carry out thedrilling operation continuously, that is to say without interruptionsfor refurbishing a drill bit or for removing a cut-free drill core, asis required in the deep drilling methods known from the prior art.

In order to be able to use a continuously operating drilling method asefficiently as possible, it is advantageous if the borehole 5 can alsobe secured and lined substantially continuously.

In order to secure the borehole 5 and also in order to shield theborehole from groundwater-conducting layers, the borehole 5 is lineddirectly after drilling. For this purpose, the borehole lining module 4according to the invention has spray nozzles 11 for applying a curingmedium, such as, for example, concrete, and a reinforcing fabric layingapparatus 12.

Use is preferably made of carbon fibers and concrete in order to producethe hybrid material serving for lining the borehole wall, but otherfiber materials and other curing media, such as, for example, plastics,are also usable for producing the hybrid material.

The reinforcing fabric laying apparatus 12 for discharging the fiberstructure can take place, for example, via a cone, via which thereinforcing fiber can be applied directly onto the borehole wall inorder subsequently to be able to be wetted with curing medium. Dependingon the depth and geological conditions, the borehole 5 can be lined withone layer or with multiple layers. The curing time of the concrete canbe accelerated by the addition of special additives. In deeper regionswith a higher earth temperature, the curing time is reduced simply bythe rise in temperature. The concrete supplied via the pipe and/or hoselines is mixed with the additives, which are likewise supplied via thepipe and/or hose lines 6, only at the borehole lining module 4, in orderto avoid curing in the supply lines.

A finished borehole lining 18 is illustrated schematically in FIG. 3.

The safety module 3 serves, in the event of a sudden rise in pressure inthe borehole 5, for example by drilling into a gas bubble, firstly toprevent uncontrolled escape of the gas from the borehole 5 and secondlyto prevent the entire drilling system 1 from being able to be pushedupward out of the borehole 5 by the rise in pressure. For this purpose,the safety module 3 has at least one locking element 13 for theform-fitting closing of the inside diameter of the borehole and clampingelements 14 for the force-fitting securing of the drilling system 1 inthe borehole 2.

The diameter of the borehole is closed in a form-fitting manner via thelocking element 13, for example with an expander ring which closes theborehole 5, in order then to be able to dissipate the positive pressurein a controlled manner via suitable pressure control valves. Theclamping elements 14 with which the entire drilling system 1 caninterlock in a force-fitting manner in the borehole 5 are designed, forexample, as barbs which face radially upward and outward and fix thedrilling system 1 in the respective position in the borehole 5 as theneed arises.

The drive and also the steering and control apparatus for the drill head2 are arranged on the drill head 2. In the embodiment illustrated, thedrive for the drill head 2 is designed as a crawler drive 15 arranged onthe outer side of the drill head 2.

In addition to the electric supply lines, the flexible pipe and/or hoselines 6, via which the drilling system 1 is connected to supply devices7 outside the borehole 5, also contains data lines, for example a bussystem, via which the drill head 2 and/or the safety module 3 and/or theborehole lining module 4 are connected to a workplace 16 outside theborehole 5.

Via said data lines, in addition to the system parameters, such as, forexample, feed speed and pumping pressure, all of the ambient parametersin the borehole 5, such as, for example, temperature, pressure, rockdensity and the like, can be determined via sensors coupled to the datalines and can be transmitted to the workplace 16 in order to control thedrilling system 1.

The control of the drilling system 1 can be arranged on only one of thecomponents of drill head 2, safety module 3 or borehole lining module 4,or else can be arranged distributed between a plurality of thecomponents 2, 3 and 4.

Since, in particular, the drill head 2 has a larger outside diameterthan the fully lined borehole 5, after the end of the drilling operationthe entire drilling system 1 remains in the borehole 5 and, after thecapping of the supply lines, can be used via the data lines whichcontinue to exist, in order to exchange data with the workplace 16.

The drilling method which is described above and is usable forgeothermal bores and for opening up natural gas or oil deposits isdistinguished in that a continuous drilling operation is made possibleand, by dispensing with drill rods and the like, requires substantiallyless outlay on material than the drilling methods known from the priorart, which leads to significantly more favorable costs for forming adeep bore.

1. A method for the chisel-less formation of boreholes for deep bores bymeans of high pressure water jet cutting, characterized by a combinationof the high pressure water jet cutting process with high frequency rockfragmentation.
 2. The method as claimed in claim 1, characterized inthat the high frequency rock fragmentation is used alternating with thehigh pressure water jet cutting or simultaneously with the high pressurewater jet cutting.
 3. The method as claimed in claim 1, characterized inthat the pressures of the high pressure water jet cutting process andthe frequencies of the high frequency rock fragmentation are variablyadjustable.
 4. The method as claimed in claim 1, characterized in thatthe wall of the borehole is continuously lined with a reinforcement. 5.A chisel-less drilling system for carrying out the method as claimed inclaim 1 with a drill head provided with water outlet nozzles,characterized in that sonotrodes for transmitting high frequencyvibrations are arranged in addition to the water outlet nozzles for thehigh pressure water jet cutting on the front end side of the drill head.6. The chisel-less drilling system as claimed in claim 5, characterizedin that the drill head, but at least an end plate of the drill head,which end plate is provided with the water outlet nozzles and thesonotrodes, is designed to be rotatable about the center axis.
 7. Thechisel-less drilling system as claimed in claim 5, characterized in thatat least one safety module and at least one borehole lining module arearranged behind the drill head in the drilling direction.
 8. Thechisel-less drilling system as claimed in claim 7, characterized in thatthe safety module has at least one locking element for the form-fittingclosing of the inside diameter of the borehole, and clamping elementsfor the force-fitting securing of the drilling system in the borehole.9. The chisel-less drilling system as claimed in claim 7, characterizedin that the borehole lining module has spray nozzles for applying acuring medium, and a reinforcing fabric laying apparatus.
 10. Thechisel-less drilling system as claimed in claim 5, characterized in thatthe drill head, the safety module and the borehole lining module areconnected to supply devices outside the borehole via flexible pipeand/or hose lines, wherein the pipe and/or hose lines serve for thesupply and removal of the materials relating to the drilling system andfor the feeding in of the electric supply lines.
 11. The chisel-lessdrilling system as claimed in claim 5, characterized in that the driveand also the steering and control apparatus for the drill head arearranged on the drill head.
 12. The chisel-less drilling system asclaimed in claim 5, characterized in that the pumps for the highpressure water jet cutting and for sucking off the flushing medium arearranged on the drill head and/or on the safety module.
 13. Thechisel-less drilling system as claimed in claim 5, characterized in thatthe drill head and/or the safety module and/or the borehole liningmodule are connected to a workplace outside the borehole via data lines,for example a bus system.
 14. The chisel-less drilling system as claimedin claim 13, characterized in that, via the data lines, in addition tothe system parameters, such as, for example, feed speed and pumpingpressure, all of the ambient parameters in the borehole, such as, forexample, temperature, pressure, rock density and the like, can bedetermined via sensors coupled to the data lines and can be transmittedto the workplace in order to control the drilling system.
 15. Thechisel-less drilling system as claimed in claim 5, characterized inthat, in order to generate the high frequency pulses for the highfrequency rock fragmentation, piezo elements which are each coupled toan amplifying unit consisting of a sonotrode and an amplitudetransformer are arranged in the drill head.